JPH0729625Y2 - Multilayer LC composite parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a laminated LC composite component, and more particularly to a laminated LC composite component having external terminals with good solderability.

[Prior Art] Small laminated inductors such as hexahedrons and LC composite parts are known. This type of laminated electronic component has thin-film external terminals on its side surface, and the electronic component is directly mounted on the printed circuit board, and solder is applied between these external terminals and the wiring on the printed circuit board surface, so-called direct wiring. It is possible to attach.

[Problems to be Solved by the Invention] However, the types of metal materials for external terminals are limited due to peeling of external terminals due to heat and mechanical force during soldering, solder affinity, and other problems.

Silver and silver alloys are commonly used for this type of external terminal because they have good adhesion to the base and good electrical conductivity, but there is a problem that silver etc. is dissolved in the solder bath when immersed in the solder bath. .
In order to prevent this, it has been attempted to form a layer of tin or the like on the surface by using silver or the like as a base layer, but a sufficiently satisfactory one has not yet been obtained.

An object of the present invention is to provide a laminated LC composite component having an external terminal with good solderability. The present invention has good conductivity, good adhesion to the base, no elution problem in the solder bath, no oxidation problem from the outside air, and high mechanical strength (difficult to peel) external terminals It is an object of the present invention to provide a laminated LC composite component.

As mentioned above, since silver or the like is an excellent external terminal but is easily dissolved in solder, the present inventor tried to coat the silver or silver alloy layer with the nickel layer by electroplating. This solves the problem of solder thinning, but in the future, the surface of the nickel layer is likely to be oxidized, and problems occur in soldering and resistance. Then, when a tin layer was further formed on the outer surface, it was found that this problem was solved. However, due to the increase in the number of layers, a peeling phenomenon was observed on the external terminals themselves. Therefore, this problem could be solved by interposing a copper layer between the silver or silver alloy layer and the nickel layer. Further, the silver or silver alloy layer was formed by the low temperature baking method, but when the other layers were formed by the electroplating method, an excellent external terminal without the above-mentioned problems was obtained. Moreover, according to the electroplating method, each layer of the external terminal is completely covered by the upper layer, and a lamination having no excess or deficiency in the periphery is obtained, so that the characteristics are improved. Therefore, the portion of the external terminal of the present invention other than the silver or silver alloy layer is limited to the electroplating layer.

[Means for Solving the Problems] The present invention is directed to an alternating laminated portion of a plurality of electrical insulator layers made of low temperature fired magnetic ferrite and a plurality of silver conductor layers for forming a coil, a plurality of dielectric layers and a plurality of capacitors. An integral sintered body including a silver electrode layer for formation and an alternating laminated body portion, the lead end of the conductor layer and the electrode layer drawn to the end face of the sintered body, and the end face connected to the lead end. There is provided a laminated LC composite component including a silver layer formed on the surface of the silver layer and an external terminal including an electroplating layer formed on the surface of the silver layer.

In this case, the electroplating layer is formed in the order of the copper layer, the nickel layer and the tin layer.

[Advantages of the Invention] (1) Low temperature firing By using ferrite, firing can be performed at a low temperature (for example, about 900 ° C). As a result, it becomes possible to perform firing by using silver without using expensive refractory metals and their alloys which have been conventionally used for capacitors and the like.

(2) Since silver is used for baking the external electrodes, disconnection of the inner and outer interfaces due to the difference in diffusion rate when different metals are used inside and outside the laminated body does not occur.

(3) As a result, deterioration of the solderability (solder wettability) of the external terminal surface can be prevented.

(4) The binder component (glass) in the silver paste requires an extra amount because the low-temperature sintered ferrite is porous, which lowers the solder wettability. By applying to the surface, improvement of solderability (wettability, strength, etc.) can be realized.

[Embodiment] Hereinafter, the present invention will be described in detail with reference to the drawings. First and second
The figure shows a laminated LC composite component, in which magnetic powder paste such as electrically insulating magnetic ferrite and silver powder paste are prepared, and a plurality of magnetic layers and a plurality of magnetic layers extending from one magnetic layer to the next layer are provided. By alternately printing the linear conductor and the linear conductor while overlapping the end portions of the conductor, a laminated body in which the conductor is wound in a coil shape is formed inside the laminated magnetic body, and further, a ferrite, a dielectric, or the like is formed. The insulating powder paste and the metal powder paste are prepared and printed in a sheet shape on the laminated body to form a laminated capacitor portion, and the whole is sintered. FIGS. 1, 2 and 3 show a laminated LC composite component after being made into a sintered body, and 1 is a laminated LC sintered body portion, which is an integral sintered body of a laminated inductor section 3 and a laminated capacitor section 2. Is made up of. The capacitor section 2 is composed of a dielectric body 4 (an insulating magnetic body may be used in some cases) and an electrode layer 5, and the inductor section 3 is composed of a magnetic body 6 and a conductor 7 that surrounds the magnetic body 6 in a coil shape. Electrode layer 5 and conductor layer 7
The lead-out ends of are exposed on both end faces of the sintered body portion 1 and are electrically connected to external terminals 8 and 9 formed by baking a silver powder paste.

FIG. 4 is an enlarged view of a main part of FIG. External terminals 8, 9
Since they have the same configuration, the external terminal 8 will be described. If necessary, the end face 10 of the sintered laminate 1 is polished by a method such as barrel polishing so that the conductor lead-out ends 11 and 12 are properly exposed on the end face 10.
A conductive coating material in which silver powder is made into a paste is applied and baked to form a base silver or silver layer 13. A copper layer 14 is formed on the silver layer by electroplating. There are various methods for performing electroplating on a small component having a partially conductive layer, and thus electroplating may be performed using any method. The copper layer 14 is interposed between the silver layer 13 and the nickel layer to be formed next, and strongly adheres both layers. Next, the nickel layer 15 is similarly formed by the electroplating method. The nickel layer 15 acts as a protective coating for the silver and copper layers and can suppress the problem of solder thinning of the external terminals. The nickel layer also adheres well to the copper layer and the subsequently formed tin layer and is chemically stable to these layers. Finally, a tin layer 16 is formed on the surface of the nickel layer 15 by electroplating. The tin layer prevents the nickel layer 15 from oxidizing. Although the tin layer 16 is easily melted in the solder bath, the presence of the nickel layer 15 can prevent the silver and copper layers from melting, and the presence of the copper layer 14 can improve the peel resistance of the external terminals.

As described above, the present invention can provide an excellent sintered laminated inductor.

[Brief description of drawings]

FIG. 1 is a sectional view of a laminated inductor according to an embodiment of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a sectional view taken along the line AA of FIG. 1, and FIG. 1: Laminated LC sintered body 2: Capacitor part 4: Dielectric body 5: Electrode layer 6: Magnetic material 7: Coil forming conductor 8, 9: External terminal 10: End face 11, 12: Lead end 13: Silver or silver alloy Layer 14: Copper layer 15: Nickel layer 16: Tin layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01G 4/12 364 4/232 4/30 301 A 9174-5E H01F 1/20 1/34 Z

Claims (1)

[Scope of utility model registration request] 1. An alternating laminated portion of a plurality of electrical insulator layers made of low temperature fired magnetic ferrite and a plurality of silver conductor layers for forming a coil, a plurality of dielectric layers and a silver electrode layer for forming a plurality of capacitors. An integrated sintered body including an alternating laminated body part, a lead-out end of the silver conductor layer and a silver electrode layer drawn out to an end face of the sintered body, and a silver formed on the end face so as to be connected to the draw-out end. Layer and an external terminal composed of an electroplating layer formed on the surface of the silver layer, and the electroplating layer is formed of a copper layer, a nickel layer and a tin layer in this order.
Composite parts.